Field of the Invention
The present invention relates to an expansion tool and method for expanding the diameter of an expandable tubular liner disposed within a targeted interval of a bore of a casing in an earthen well. More specifically, the present invention relates to an expansion tool and a method to expand an expandable tubular liner along its full length. The expansion tool and method of the present invention provide for an improved installation of an expandable liner to seal with the casing without the necessity and expense of recovering a residual and/or non-expanded portion of the tubular liner from the well to prevent well obstruction. The present invention further relates to an expansion tool and a method for positioning and then restraining the expandable liner within the targeted installation interval of the casing during a stepwise or staged expansion of the liner to engage and seal the targeted interval of the casing.
Background of the Related Art
Various tools and methods have been devised for expanding a tubular disposed in an earthen well including, but not limited to, those disclosed in U.S. Pat. Nos. 7,225,880, 7,278,492 and 8,132,627. Some tools are intended to provide a tubular patch in a well, as disclosed in U.S. Pat. Nos. 6,622,788, 6,763,893 and 6,814,143.
An expandable tubular liner used for lining a targeted interval of a well casing may be installed within a casing to provide added structural and/or sealing integrity to an unstable or leaking interval of a casing. An expandable liner may be installed in a targeted interval of casing to isolate a previously perforated, leaking or otherwise open interval of the casing to prevent fluid exchange between the well and one or more adjacent geologic formations penetrated by the well.
Expandable liners may be installed within a targeted interval of a well casing by running an undersized (unexpanded) liner into the targeted interval of the well casing and radially outwardly expanding the liner in-situ. Conventional liner expansion tools include a pulling mandrel that pulls an expander, larger in diameter than the unexpanded liner, from a distal (downhole) end of the liner towards a proximal (uphole) end of the liner. Other liner expansion tools include pushing a mandrel that pushes a connected expander from a proximal end of the liner towards a distal end of the liner. Still other expansion tools rely on hydraulic pressure to generate a force sufficient to displace an expander through the bore of a liner without the use of a mandrel to pull or push the expander.
The liner material and the liner dimensions are generally selected to yield radially outwardly as the expander is moved through the bore to radially expand the liner and to engage the expanded liner with the bore of the targeted casing interval without rupture. The elastic limit of the liner material is exceeded to produce plastic deformation of the liner and to cause the liner to retain an expanded diameter engaged with the bore of the casing. It will be understood that the liner may be expanded slightly beyond the intended diameter in order to elastically resist a residual collapsing force applied by the casing after the expander passes. This mode of installation is optimal for improving the sealing integrity between the exterior surface of the expanded liner and the interior bore of the casing.
Some conventional expansion tools and method involve pulling or pushing the expander through the bore of the expandable liner by engaging the expander on a distal end of an elongate mandrel that is slidably received through a bore of a housing. The mandrel may be hydraulically displaced within the housing to pull the expander into and then through the bore of a liner disposed axially intermediate an expander, connected at the distal end of the mandrel, and a reaction assembly on the expansion tool to oppose movement of the liner during expansion. The expansion tool may be secured or coupled within the casing using a gripping device. The housing and the mandrel may each include a variety of additional features including, but not limited to, annular pistons, annular chambers, connectors, fittings, ball seats and apertures.
A shortcoming of conventional liner expansion tools is that if the slips of the tool are set within the bore of the expandable liner, and if the expandable liner is expanded beginning at an end of the expandable liner that is spaced apart from the portion of the expandable liner in which the slips are set to secure the expandable liner in position, the slips must be eventually displaced from the bore of the liner. This presents a problem because the expandable liner cannot be secured in position for expansion of the full length of the expandable liner, and a portion of the expandable liner will remain in the unexpanded condition. The unexpanded portion may require an additional trip into the well to retrieve the unexpanded portion of the liner.
Those skilled in the metallurgical arts will understand that a metal liner that is radially outwardly expanded to a larger diameter exhibits a predictable amount of axial shrinkage. As the diameter of the liner is expanded, the wall thickness of the liner is substantially reduced and the length of the liner shortens to compensate. This shrinkage may complicate the liner expansion process where slips are set in the bore of the casing above the top of the expandable liner and are used to secure the liner in position against the expander. Shrinkage of the liner may cause unwanted movement or shifting of an expanded portion of the liner within the casing if the reaction assembly cannot be favorably repositioned to compensate for axial shrinkage of the liner, thereby compromising the sealing integrity of the expanded liner. Conventional expansion tools that grip the bore of the expandable liner during liner expansion include reaction assemblies that remain in a fixed position within the liner during liner expansion, resulting in a loss of sealing integrity between the expanded liner and the casing due to the axial shrinkage that occurs during expansion of the liner bore.
The disadvantages of the prior art are overcome by the present invention, an improved downhole tubular expander and method are herein disclosed.